1. Field of the Invention
The present invention relates to a ratchet spanner, more particularly to a ratchet spanner which includes components that can be easily assembled during the manufacturing process thereof and which requires little operating space to operate the same.
2. Description of the Related Art
Referring to FIGS. 1 and 2, a conventional ratchet spanner is shown to include a spanner body 1 and a ratchet mechanism. The spanner body 1 has an annular head portion 101 defining a ratchet accommodating chamber 102 with a lower end opening. The ratchet mechanism includes a ratchet wheel 105 disposed rotatably in a front section 103 of the chamber 102 via the lower end opening such that a tool mounting shank 105" of the ratchet wheel 105 projects outwardly of the chamber 102. Two spring-biased pawls 107 and a pawl actuator 106 are disposed in a rear section 104 of the chamber 102 and are operably connected to the ratchet wheel 105. The pawl actuator 106 can be manually operated in either one of two directions in order to engage a selected one of the pawls 107 with the ratchet wheel 105 such that the conventional ratchet spanner is turnable in only a single direction when in operation.
Some of the drawbacks of the aforementioned conventional ratchet spanner are as follows:
It is somewhat difficult to assemble the components of the aforesaid ratchet spanner. During assembly, after the ratchet wheel 105, the spring-biased pawls 107 and the pawl actuator 106 are mounted in the chamber 102, a cover shield 109 is mounted on the spanner body 1 by the use of screws 109' to prevent downward removal of the ratchet wheel 105 from the head portion 101 of the spanner body 1. As such, a relatively long assembly time is incurred.
In addition, because the ratchet wheel 105 has a relatively small number of teeth 105' with great pitches, in order to ensure engagement between a rectangular end 107' of the pawls 107 and the teeth 105 ' of the ratchet wheel 105, a large amount of operating space is needed for turning of the spanner body 1.
Referring to FIGS. 3 and 4, another conventional ratchet spanner is shown to include a spanner body 2 and a ratchet mechanism. The spanner body 2 includes an annular head portion 201 which has a peripheral wall 201A with top and bottom ends and an opening 202 formed through the top and bottom ends, and top and bottom flanges that extend radially and inwardly from the top and bottom ends. The ratchet mechanism includes a ratchet wheel 205 that is disposed rotatably within the opening 202 in the head portion 201 and that defines a tool accommodating cavity at the central portion thereof, a pawl unit 206 disposed within the opening 202, and a spring unit 207 that is disposed within a retention bore 204 formed in the peripheral wall 201A and that biases the pawl unit 206 to engage teeth 205 ' of the ratchet wheel 205.
Because the ratchet wheel 205 is provided with densely located fine profile teeth 205 ', only a small amount of operating space is required to operate the aforesaid conventional spanner. However, during the manufacture of the ratchet wheel 205, high precision and great skill are needed to produce such type of fine profile teeth 205'. A high manufacturing cost is thus incurred.
During mass production, a curved recess 203 is firstly formed in the peripheral wall 201A. The retention bore 204 is then formed by a milling unit and a drilling unit. Since only a small-diameter cutting tool can be used in order to form the retention bore 204 with a relative depth, the cutting tool easily breaks under high speeds of rotation, thereby inconveniencing the operator.